Update Contributor source plugin to list all fields

Problem/Motivation

The "biblio_contributor_data" table includes several columns that are not exposed through the Contributor source plugin.

Proposed resolution

Add all fields to the Contributor source plugin for the biblio_contributor_data table.

Remaining tasks

Provide a patch with the necessary changes.

User interface changes

People building custom migrations have access to all fields.

API changes

n/a

Data model changes

n/a